The present invention relates generally to a system and method for efficiently using bandwidth across a fixed interface. The invention provides a system and method for monitoring one or more attributes of communication traffic on one or more channels operating across the interface and assigning or removing bandwidth from the one or more channels based on the monitored attributes. A preferred embodiment of the invention dynamically assigns bandwidth for one or more DS0 voice channels across a fixed interface in a configurable multi-channel communication system using T1 and/or E1 trunks. It shall be understood that the term T1/E1 as used herein shall refer to any multiplex source and not just a T1 or E1 source. Bandwidth for voice channels is assigned as a function of the ACTIVE/IDLE bits associated with the DS0 channels and only those voice channels that are active are assigned bandwidth. Channels carrying data only are not impacted by the present invention.
Typical multi-channel communication systems use a channelized T1 or E1 trunk line comprising a number of DS0 channels where each DS0 channel carries data at a rate of 64,000 bits per second, or 64 Kbps. A typical T1 line is composed of 24 DS0 channels carrying a total of 1.536 Mbps of available bandwidth for carrying communication data, plus 0.008 Mbps of framing bits which are typically unavailable to carry communication data, for a total of 1.544 Mbps throughput. A typical E1 channel is composed of 30 DS0 channels plus 2 control channels for a total throughput of 2.048 Mbps. Some E1 channels are composed of 31 DS0 channels and 1 control channel. The channelized nature of such T1/E1 systems ensures that any given channel is assigned bandwidth for use only by that channel and therefore bandwidth is always available for the exclusive use of the subscriber on that channel. While this manner of dedicating bandwidth to channels ensures availability of bandwidth for each subscriber using the system, it also introduces inefficiencies in the system during times when less than all the channels are actively being used to transmit communication information.
As an example of the inefficiencies introduced into a communication system by dedicating bandwidth to specific channels, if a T1 trunk line comprising 24 DS0 channels is operating with 12 of the channels idle, i.e., not actively passing a subscriber""s communication information across 12 of the channels, approximately only half of the available bandwidth would be utilized by the communication system. The remainder of the available bandwidth would go to waste. This is particularly a problem in systems which have a wireless interface, such as a broadband wireless access system, since wireless spectrum is a valuable, expensive, and scarce resource. However, the problem is similar in wired systems where an interface between communication systems operates as a choke point due to a limitation in available bandwidth across the interface.
A typical scenario exemplifying the problem of wasting bandwidth on idle channels includes systems where voice channels are used intermittently by subscribers. When a voice subscriber goes off-hook, thereby placing the channel in an active state, the channel is used to carry voice information between the subscriber""s calling party and called party. Once the call terminates, typically by the parties going on-hook, the channel is no longer actively passing subscriber communication information. If the bandwidth assigned to the channel remains dedicated to that channel, the bandwidth is wasted until such time as the subscriber re-initiates a call by going off-hook.
One of the problems faced by typical prior art communication systems is a lack of available bandwidth to satisfy the demands of the subscribers on the system. Prior art communication systems tend to overcome the lack of bandwidth by adding more channels, perhaps even adding one or more T1/E1 lines to match the subscribers bandwidth needs. However, this type of brute force solution merely aggravates the inefficiencies of the system and results in even more bandwidth going to waste.
One way to overcome the inefficiency described above is to dynamically allocate available bandwidth for voice subscribers only to those voice subscriber channels that are active at any one time, as is done by the present invention. There are a number of advantages to be realized by implementing a communication system that does not reserve dedicated bandwidth to a particular subscriber. One advantage is that since voice subscribers typically do not use a channel one hundred percent of the time, more subscribers may be added to a particular communication system without the need to add more T1 or E1 lines. Another advantage is that the bandwidth that would otherwise be dedicated to an idle voice channel can be used to increase the bandwidth of the active voice channels.
One embodiment of the present invention avoids the problems of the prior art by dynamically assigning bandwidth to active voice channels across an interface thereby increasing the bandwidth use efficiency of the system. Another embodiment of the present invention dynamically assigns bandwidth for a digital communication channel in an N channel communication system where the communication signal being transmitted includes a protocol data unit with N activity bits, one activity bit for each channel, which indicate whether the associated channels are active or idle. The activity bits are monitored and if a change in an activity bit is detected and that change persists for a predetermined time interval, the active/idle status of the channel associated with that activity bit is changed as well as the assignment of bandwidth to that channel. For example, if a channel was in an ACTIVE state, and therefore was assigned bandwidth, the detection of a persistent change in the activity bit associated with that channel would indicate that the channel is now IDLE and bandwidth would not be assigned to the channel. Similarly, if a channel was in an IDLE state, and therefore no bandwidth is assigned to the channel, the detection of a persistent change in the activity bit associated with that channel would indicated that the channel is not ACTIVE and bandwidth would therefore be assigned to the channel.
Accordingly, it is an object of the present invention to obviate many of the above problems in the prior art and to provide a novel system and method of assigning bandwidth to one or more voice channels in a multiple-user broadband wireless access communication system in response to a predetermined value of one or more signaling bits associated with the voice channels.
It is another object of the present invention to provide a novel method of assigning bandwidth to at least one communication channel in a configurable multi-channel communication system having a wireless transmission interface including at least one remote station and a base station where the traffic in the communication channels includes at least one active/idle bit indicating the status of the channel.
It is yet another object of the present invention to provide a novel system and method for dynamically monitoring the Channel Associated Signaling Bits (xe2x80x9cABCD Bitsxe2x80x9d) and assigning bandwidth over a wireless interface based on the value of the ABCD bits.
It is still another object of the present invention to provide a novel system and method for efficiently assigning bandwidth over a wireless transmission interface for voice channels in a multi-channel communication system.
It is a further object of the present invention to provide a novel system and method for the efficient us of channel bandwidth for one or more voice subscribers using a T1 or E1 trunk across a fixed wireless interface.
It is yet a further object of the present invention to provide a novel method of dynamically assigning bandwidth for a plurality of DS0 communication channels in a digital multi-channel communication system including receiving digital information containing a signaling byte for each of a plurality of communication channels, providing a protocol data unit capable of carrying the digital information, monitoring the information in select ones of said signaling bytes, modifying the protocol data unit as a function of the information in the select signaling bytes, and assigning bandwidth as a function of the modified protocol data unit.
It is still a further object of the present invention to provide a novel system and method for efficiently assigning bandwidth across a wireless interface including refraining from assigning bandwidth for voice channels that are in an INACTIVE state.
It is an additional object of the present invention to provide a novel system and method for dynamically assigning bandwidth for a digital communication channel in a configurable N-channel communication system in which the communication signal includes plural protocol data units each having N bi-state activity bits in predetermined positions within the protocol data unit where each of the activity bits indicates the state of one of the N communication channels.
It is yet an additional object of the present invention to provide a novel system and method for dynamically assigning bandwidth in a multi-channel communication system in which the communication signal includes plural protocol data units each having a bi-state activity bit for each channel in predetermined positions within the protocol data unit where each of the activity bits indicates the state of one of the multiple communication channels where the activity bits are monitored in successive protocol data units such that if a change in the state of one of the monitored activity bits is detected the state of the channel associated with the monitored activity bit is changed in the absence of a subsequent change in the state of the activity bit during a predetermined time interval initiated by the detection of the change of state of the monitored activity bit to thereby vary the assignment of bandwidth to the channel associated with the monitored bit.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the preferred embodiments.